Title: Enteral feeding in Crohn's disease
Key words: avian mycobacterium, incidence, anti-tuberculosis treatment, steroids, surgery, parenteral nutrition, exclusion diet, Bifidobacteria, selenium,
Date: June 2001
Category: Special diets
Author: Dr M Draper
Enteral feeding in Crohn's disease
A recent article in the Daily Mail entitled: 'Make milk safer, food watchdog tells dairies'(1) states the case that an avian Mycobacterium Paratuberculinum, a bacteria that can survive the pasteurisation (to 72 degrees) of milk and which causes Johne's disease in cattle, is becoming a zoonosis responsible for causing Crohn's disease in humans. The organism can be cultured from the breast milk of patients with Crohn's disease (2). This strengthens the hypothesis of Prof. John Herman -Taylor who is of the opinion that the sixfold increase in the disease since the 1950's can be attributed to this organism. The incidence of the disease, which often affects young adults and children, is 2.6 per 100,000 in Welsh children (3) with a mean age of presentation of 12 years old. Evidence from 2 small trials of anti-tuberculosis treatment maintaining remission induced by steroids should be interpreted with caution (4). Clinicians are trying to reduce the use of steroids (5) and the evidence will be reviewed for the use of enteral feeding in the management of Crohn's disease.
Evidence for Enteral Feeding:
Patients with severe Crohn's disease are often admitted to hospital (6) because of abdominal pain, diarrhoea and weight loss. Surgery is a considered option when steroid therapy has failed to induce remission or was contraindicated due to potential osteoporotic effects (7). Prior to surgery, parenteral (intravenous) therapy was used to improve nutritional status and it was noted by physicians that this could induce remission. Enteral therapy offers a cheaper, safer and simpler alternative, even if it may be less palatable for the patient.
A comparison of Total Parenteral Nutrition and Elemental Diet (8) without pharmacological support was successful and showed no difference in the number of days to remission or the mean changes in Crohn's activity index, ESR or serum albumin. In this study, the development of a personal food exclusion diet appears to be an effective long-term therapeutic strategy with average annual relapse rates of only 11% for the first five years of diet alone. The foods excluded have been predominantly cereals, dairy products, and yeast (9,10). The mechanism of action of elemental diets is unclear. Alteration of bacterial flora, low antigenicity, low fat and supplementation of essential micronutrients have all been proposed. Bifidobacteria are decreased in Crohn's disease (11) These normally produce short chain fatty acids that are known to have an anti-inflammatory effect. Comparison of four elemental feeds (12) concluded that the inflammatory indices were reduced less if the feed had long chain fatty acids. Studies comparing whole protein versus amino acid enteral feeds showed no difference in remission rates and it appears that very low residue is important especially in patients with strictures (13). Polymeric enteral feeds do not offer an effective alternative to elemental diets in patients with acute Crohn's disease (14) and others conclude that enteral nutrtion, whatever the diet does not influence long term outcome (15). However, maintaining micronutrient status, especially selenium levels as T4-T3 conversion is selenium dependent and affects immune status in animals against TB, must be important if Crohn's disease is a mycobacterium paratuberculinum infection. Malnutrition and poor absorption may contribute to reducing host defence mechanisms.
Corticosteroids (16) and other forms of drug treatment (17) appear to be more effective than enteral feeding (contested 18). However in children, adolescents and those with low bone density (especially women) enteral feeding may be considered the therapeutic treatment of choice but it requires motivation and is expensive.
References (1) Poulter, S. (2001) Daily Mail 20 June 2001.
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(3) Hassan, K. et al. (2000) The incidence of childhood inflammatory bowel disease in Wales.'Eur J Pediatr, 20004, 159: 261-3.
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(10) Riordan, A.M. et al. (1993)'Treatment of active Crohn's disease by exclusion diet: East Anglican Muticentre Controlled Trial.'Lancet 342: 1131-4
(11) Favier, C. et al. (1997) Fecal beta-D- galactosidase Production and Bifidobacteria are decreased in Crohn's disease.'Digestive Diseases and Sciences, Vol 42: p817-822.
(12) Middleton, S.J. et al. (1995) 'Long chain triglycerides reduce the efficacy of enteral feeds in patienets with active Crohn's disease.'Clin Nutr 14: 229-236.
(13) Raouf, A.H. (1991) 'Enteral feeding as sole treatment for Crohn's disease: controlled trial of whole protein v amino acid based feed and a case study of dietary challenge.' Gut 32:702-707. (14) Giaffer, M.H. et al. (1990) 'Controlled trial of polymeric versus elemental diet in treatment of active Crohn's disease.'Lancet Vol 335: 816-819.
(15) Rigaud, D et al. (1991)'Controlled trial comparing two types of enteral nutrition in treatment of active Crohn's: elemental v polymeric diet.'Gut 32: 1492-1497.
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